Fix launch of matrix-bridge-irc.

[damomurf]

This resolves the issue I experienced in #44. The latest versions of the matrixdotorg/matrix-appservice-irc container image launches the node.js process with incompatible defaults as below. This PR will allow the chart to work out of the box with the default values.:

Container defaults:

exec node app.js -c /data/config.yaml -p 9995 -f /data/appservice-registration-irc.yaml -u http://localhost:9995

This PR changes the execution to:

          command: "node"
          args: [ "app.js", "-c", "/data/config.yaml", "-f", "/data/appservice-registration-irc.yaml" ]